The mesolimbic and cortical dopamine (DA) systems have been a recent focus of the hypothesized relationship between DA and schizophrenia. By use of combinations of electrical stimulation, single unit recording, microiontophoresis, and histochemical techniques, we propose first to identify and characterize A-10 DA neurons and then elucidate possible influences of specific neurotransmitter systems and mode of action of drugs such as d- and l-amphetamine on these identified A-10 DA cells in the rat. These studies should provide basic information about neurophysiology of A-10 DA neurons and its circuitry, clarify our knowledge of neurochemical basis of amphetamine psychosis and further our understanding of neurotransmitter systems which control A-10 DA activity. Ultimately, such knowledge should (1) contribute to the identification of neuronal systems which may be involved in the pathogenesis of schizophrenia, and (2) lead to the development of new antipsychotic agents with less risk of tardive dyskinesia and other side effects, and thus provide better pharmacotherapy to psychotic patients.